Q. How do I find the variable costs for a product?

Typically you won't be able obtain prices for component parts of a product.

To estimate the variable costs of a product use the Financial Performance Data Tool. 

This website provides figures on what % of revenue goes to particular costs in different industries (e.g. rent, insurance etc). It also provides an average “gross margin” (a relative measure of profitability or profit margin). 

To use this tool you’ll need to know the NAICS (North American industry Classification System) for your industry.